Telephone systems have employed voice mail or similar message technology for quite some time. Voice mail and messaging technology enables a called party to receive a message when they do not answer their telephone. The called party can retrieve the message at some later point in time.
Initially, the answering machine presented a called party with a way to record messages when they were unavailable to answer the telephone. Typically, the answering machine makes an analog recording of the calling party's message. Most answering machines are devices that plug into a telephone jack at the called party's location. Newer versions of answering machines allow for digital recording of messages and may even permit multiple mailboxes to be set up on a single telephone line.
More recently, telephone companies have offered digital voice mail services. A customer of the telephone company can subscribe to a digital voice mail service and have messages recorded by the telephone company that they can retrieve from their home telephone or from a telephone away from their home. Computer software and other hardware have been developed to provide called parties with a variety of voice messaging capabilities.
Not all telephone users subscribe to voice mail services or have answering machines. If a called party does not have a voice mail service or an answering machine, a calling party cannot leave a message for the called party. In some situations it may be desirable to provide a calling party with the ability to leave a voice message for the party being called, even when the called party does not have a voice mail service (or is not associated with such a service), an answering machine, or a message recording device.